Bill Mason started selling baseball cards 25 years ago by carving a small space in his father’s convenience store, hoping to grab the attention of customers as they bought lottery tickets or paid their utility bill.

He had become enamored with collecting after scoring autographs at Veterans Stadium, and this — hawking packs of cards after he turned 18 in the summer of 1996 — was a chance to turn that passion into profit. The business grew, eventually moved to its own building next door, and Bill’s Sports Cards and Memorabilia became a mainstay in Northeast Philly.

But the outlook of Mason’s business — and the entire sports card industry — felt a bit dire in March 2020 in the early days of the coronavirus pandemic.

“I was sitting here and saying, ‘Man, sports are done. People aren’t going to have money. We’re going to have to close the store for a little bit,’ ” Mason said at his store on Rhawn Street. “I didn’t know how this was going to play out.”

Seventeen months later, it has played out better than Mason could have ever imagined. The trading card industry boomed during the pandemic as collectors rediscovered the hobby or dug even deeper into it while the world was shut down.

Cards starting moving like stocks as values for rookie cards and rare vintage cards spiked on resale markets such as eBay. Packs and boxes became so hard to find that collectors were able to flip them for double or triple the retail price.

Topps, the leading card company, was valued earlier this year to be worth $1.3 billion. Of the 25 most expensive sports card sales, 24 of them have been made since the start of 2020. The industry boomed.

“The current marketplace since COVID has been freaky. It’s just been completely overwhelming,” said Steve MacKenzie, who owns Horsham’s Knuckleball Sports Cards. “My sales since last July when I reopened my store have probably tripled since before COVID.”

“I’ve been here 11 years. Nine of them, I didn’t make any money or I lost money. But this year is going to be an exception. Last year, I made money. It’s going in the right direction. The market is very strong right now and I think a lot of people are home and you finally have time to say, ‘I think I have my old cards in my attic somewhere.’ You dig them out, and you’re into it again.”

While many industries took a hit during the pandemic, trading cards and memorabilia actually benefited. The industry is accustomed to peaks and valleys, but this is a higher peak than local store owners had ever seen. Their fears at the start of the pandemic were for naught.

“I’ve never seen a thing like it. At the beginning of the pandemic, I was locked down. Nobody was allowed in,” said Jim DeCorso, who has owned Media Cards & Sports since 1993. “People had time. They decided to work on their collection. They also saved a lot of money. They weren’t renting hotels, going on vacations, and buying plane tickets, so they had a lot of disposable income.”

“I’ve had stuff for years. Sometimes I’ll put stuff out and it doesn’t sell. I’ll store it away, forget about it, put it back out. Now, everything sells.”

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Mason tries to schedule an autograph signing once a month, usually bringing a current or former Philly athlete to his shop. The pandemic forced the cancellation of in-person events, but the signings he scheduled — collectors would send items to Mason for him to give to players — outpaced the ones he held before the pandemic.

And it wasn’t just the stars who have created buzz during the pandemic. Mason said collectors used the pandemic to comb through their sets and see which signatures they were missing. So even a player such as Gregg Jefferies, a solid player but not a superstar, became so popular that Mason had to arrange a second signing. Mason had more than 3,000 items sent to him for Jefferies to sign.

“That would never happen before,” Mason said. “It was like that for so many players over the last year.”

Carl Henderson, who opened his Havertown shop in 1995, said the current market is “the high end of things.” Carl’s Cards and Collectibles was closed for nearly four months last year because of the pandemic, forcing Henderson to get creative just like the other shop owners.

Mason held weekly auctions on Facebook, and Gerber stores such as Heidi and Steve Gerber’s Sportscard Playground in Hatboro held box-breaking events online. Henderson created “mystery boxes” and sold some of the vintage cards in his own collection to make sure his bills were paid. His store reopened last summer, and business was better than ever.

“We survived,” Henderson said. “Business is thriving now. Business has really come back. People are back into collecting.”

“A lot of kids were home from school, home from college; they kind of realized ‘I can buy and resell,’ so a lot of that happened. A lot of situations where they dug back into their childhood collections and said, ‘Man, I can make some money from this.’ That’s really it. It took off.”

There have been other high times for trading cards. They peaked in the 1980s, declined in the early ‘90s, and have had ups and downs ever since. So it has some wondering if this pandemic boom is really just a bubble waiting to burst.

“I think there will be a market correction, but I think it’s always going to be stronger than it ever was,” Heidi Gerber said. “There’s too many people who have a respect for like key cards and key rookie cards and want them for their investment portfolios. The industry is just really, really healthy.”

“I think there’s a lot more collectors now,” Mason said. “A lot more kids are back into it now. With the way things are with selling online, people are seeing that they can make money off this. It’s going to continue for at least a year.”

Gerber closed the doors to her Hatboro store for more than a year as the pandemic forced Sportscard Playground to rely on curbside pickups. So imagine how the Gerbers felt earlier this month when they held their first in-store event since the pandemic hit and a line of customers waited outside throughout the afternoon.

They regularly held events before the pandemic, but never had crowds like this. Business was back, and for local shops, it’s never been better.

“It was pretty amazing,” Heidi Gerber said. “I don’t know what else to say besides it was amazing. It definitely confirms your faith in the hobby and how strong it is.”